Thermoacoustic engines offer a promising method for converting low- to medium-grade heat into useful work, manifesting as electrical power or mechanical motion. This capability facilitates their integration with complementary technologies. However, integrating the engine with a load, such as a membrane or a piston, can introduce nonlinear effects and disrupt the acoustic field. In this thesis, two thermoacoustic systems with novel design concepts were the subject of research: 1) a standing-wave thermoacoustic engine coupled with a synthetic jet, where the engine acts as an actuation mechanism, and 2) a thermoacoustic electric generator based on a forward-thinking seed-harvest concept.The standing-wave engine, TACoJEN, was first studied in its uncoupled condition under various geometrical configurations, such as resonator length (LR = 870–1620 mm) and relative stack position (XS/LR = 5.52%–25.61%), to identify the development of nonlinear effects at different conditions. Following this, the engine was coupled with the synthetic jet to characterize the jet performance based on the engine's configuration. The determining parameters in this phase of research were temperature difference (ΔT), drive ratio (DR), and peak jet velocity. Moreover, the emergence of nonlinear harmonics in tests was quantified using the Variational Mode Decomposition technique and power spectrogram analysis. Following this experimental phase, a Thermoeconomic analysis of the system was conducted. In addition, the morphological aspects of the jet and its decay were characterized using a Large Eddy Simulation.At a resonator length of 1070 mm and relative stack position of 10%, a jet velocity of 78 m/s was achieved at a minimum ΔT of 256 °C. Integrating an elastic membrane had a powerful effect on the acoustic field. Discrepancy in phase between membrane vibration and acoustic pressure fluctuations had the potential to delay the start of oscillations within the engine. This effect can be controlled through adjustments in resonator length or operating frequency. Higher velocities, up to 92 m/s, were obtained when the stack was positioned closer to the pressure antinode. However, this necessitated a greater ΔT while simultaneously introducing non-linear phenomena like the membrane's panting response. Pronounced involvement of higher harmonics within the system was detected once the core was placed at XS/LR < 9%, where DR>6%. Given thermoeconomic analysis, the system could recover a maximum of 6.2 W of power from 197 W provided at the thermal efficiency of 3.2% and exergetic efficiency of 7%. The findings prove the system's potential as a future thermal management solution and underscore the high sensitivity of jet performance to the thermoacoustic design parameters.In the second research phase, a thermoacoustic generator, HARP2, was experimentally tested. According to the DeltaEC-aided design, the device was supposed to deliver 180.1 W of power from a 21 W input, with the acoustic power magnified via 3 cores between the seed and harvest terminals. The first aim was to experimentally validate this concept and analyse the device's performance sensitivity to key control parameters, including the motor’s actuation frequency, amplitude, and the resistive load on the linear alternator. At design point operation (actuation frequency and amplitude of 60 Hz and 1.5 mm), the generator produced a 52.2 W output from a 26.5 W input, achieving a maximum power amplification rate (PAR) of 1.76. A significant viscous resistance was imposed on the acoustic field by the inertance tube, and the dissipation of acoustic work along this component accounts for the notable deviation of the experimental results from the design point. Specifically, the tube's long length and coiled shape, which primarily served as a phase adjuster, were the main reason for this behaviour.A performance sensitivity study was conducted on the device, considering the effects of load resistance, actuation frequency, and amplitude of the linear motor. The maximum PAR of 1.97 was achieved at an actuation frequency of 58.2 Hz, a resistive load of 8 Ω, and an amplitude of 1 mm. At this optimal point, the impedance phase angle of the alternator and the acoustic wave aligned well with the design specification defined for the alternator itself. In the end, although the experimental results deviated from the model predictions, this research successfully validates the core concept of amplifying a small acoustic power through a multi-staged thermoacoustic generator.